1. Field of the Invention
The present invention relates to a resist composition suitable for lithography and the like acting by high-energy radiation such as ultraviolet ray (including g ray (436 nm), i ray (365 nm) and the like), far ultraviolet ray (including excimer laser and the like), electron beam, X ray or radiation light.
2. Prior Art
In the fields of producing semiconductor elements and liquid crystal elements, formation of patterns of high sensitivity and high resolution is required in photo resists necessary for fine processing of integrated circuits because of enhanced integration of integrated circuits. Recently, as a resist capable of attaining high sensitivity and high resolution, adopted are so-called chemical amplification type resists utilizing an acid catalysis and chemical amplification effect. With the chemical amplification type resist, acids generated from an acid generator in parts irradiated with radioactive ray are diffused by the post exposure bake (hereinafter, sometimes abbreviated as PEB), and the solubility of the irradiated parts in an alkali developer is changed by a reaction using the acid as a catalyst, and thereby positive or negative patterns are obtained.
In the chemical amplification type positive resist, when resin which itself is insoluble or poorly soluble in an alkali aqueous solution but becomes soluble in an alkali aqueous solution after dissociation of acid-labile group by the action of an acid is used, resolution is generally increased as the rate of protection by the acid-labile group is increased. However, such increase of protection rate tends to cause increase of patterns of standing wave (concave and convex of side walls), deterioration of line edge roughness of patterns and increase of irregularity in processing dimension. When the transmittance of photo resist is lowered for decreasing the patterns of standing wave or decreasing line edge roughness of patterns, the resolution tends to be deteriorated.